Comparative study of microfossils from two kinds of sediments: chert intercalations (studied in thin section) and phosphorite/phosphatic carbonate (in thin section and maceration), from the upper Neoproterozoic Doushantuo phospho− rites in the Weng’an area, Guizhou Province, South China, shows that the phosphatized Megasphaera ornata and the chert−preserved Tianzhushania tuberifera should be re...

Our understanding of frictional melting that occurs during large earthquake slip events has been hampered by the extremely fine-grain size of frictionally fused rock, and the lack of detailed high-resolution microscopy studies that describe features at the crystal lattice scale. In such a study, we here report the complex nature of melting and crystallization in a symmetrically layered, pseudot...

Public concerns about oil and natural gas extraction these days inevitably turn to hydraulic fracturing, where millions of gallons of water, sand, and chemicals are pumped underground at high pressures to crack open rocks. Hydraulic fracturing often occurs a mile or more down, far from the water we drink or the air we breathe. The focus for safety and environmental stewardship should often be s...

Abstract In conventional mud drilling, sufficient drilling fluid density is required to maintain wellbore stability. However, in gas the support ability of very weak, and stability usually good. This shows that borehole instability mechanism different from drilling. wall rock still has a certain bearing capacity after reaching peak strength. this paper, studied by using complete stress–strain m...

The term “geomechanics” means different things to people. We assert that in the petroleum industry broad consensus for a definition would probably be something like this: Geomechanics is discipline investigates rock mechanical behavior subsurface (i.e., at wellbore wall, overburden, cap rock, and/or reservoir) under present-day in-situ stress and pore pressure conditions or those changed throug...

In view of the problems associated with poor stability coal walls, slide and leakage top-coal at tunnel excavation working face under a soft extra-thick roof, surrounding rock must be strengthened. The theoretical analysis pressure, numerical simulation other methods were comprehensively used to study coal-wall-slicing mechanism. Given characteristics combined supporting technology “coal wall w...

Upper urinary tract peristalsis is generated in the proximal renal pelvis that connects to the renal parenchyma at the pelvis-kidney junction. It may be exposed to the high renal endothelin-1 (ET-1) concentrations. Dietary NaCl restriction increases renal pelvic ET(A) receptor expression. We investigated the contribution of ET(A) and ET(B) receptors to ET-1-stimulated rat renal pelvic contracti...

The purpose of this paper is to report the results of a new model study examining the high temperature nuclear waste disposal concept at Yucca Mountain using MULTIFLUX, an integrated indriftand mountain-scale thermal-hydrologic model. The results show that a large amount of vapor flow into the drift is expected during the period of above-boiling temperatures. This phenomenon makes the emplaceme...